Many of the following chapters combine factual descriptions with future scenarios based on those facts. Facts and possibilities by themselves can be dry and disconnected from human affairs; scenarios are widely used by business strategists to link facts and possibilities into coherent, vital pictures. We adopt them for this purpose. Scenarios are distinguished from the surrounding text by indentation. Where they speak of technologies, they represent our understanding of what is possible. Where they speak of events occurring before 1991, they represent our understanding of what has already happened. Other elements of scenarios, however, are there to tell a story. The story in first two paragraphs, set in 1990, is fact.